In a mobile communication system employing an LTE (Long Term Evolution)-Advanced scheme which is the next generation of an LTE scheme, a “relay node RN” having the same function as that of a radio base station DeNB (Donor eNB) may be connected between a mobile station UE and the radio base station DeNB.
The LTE-Advanced mobile communication system is configured such that E-RAB (E-UTRAN Radio Access Bearer) is set between the mobile station UE and a core node CN (Core Node), a Uu radio bearer is set between the mobile station UE and the relay node RN, a Un radio bearer is set between the relay node RN and the radio base station DeNB, and an S1 bearer is set between the radio base station DeNB and the core node CN.
However, in the mobile communication system, when a process (a reception process in the Un radio bearer) of receiving by the relay node RN a downlink signal from the radio base station DeNB is simultaneously performed with a process (a transmission process in the Uu radio bearer) of transmitting by the relay node RN a downlink signal to the mobile station UE, or a process (a reception process in the Uu radio bearer) of receiving by the relay node RN an uplink signal from the mobile station UE is simultaneously performed with a process (a transmission process in the Un radio bearer) of transmitting by the relay node RN an uplink signal to the radio base station DeNB, a transmission signal of the relay node RN may loop around its own reception circuit, resulting in a problem that interference occurs.